1. Field of the Invention
This invention relates to a polarized white light source based on light-emitting semiconductor devices.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification by one or more reference numbers within brackets, e.g., [Ref(s). x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)
The use of the present invention is for obtaining polarized white light based on semiconductor light-emitting devices such as light-emitting diodes (LEDs) and laser diodes (LDs). The LED includes super luminescent diodes (SLDs), which is a similar device to the LED. The applications for this embodiment of the present invention include, but are not limited to, display backlighting, two- and three-dimensional image projectors, and architectural lighting applications that require uniform color illumination.
Many LEDs show strongly polarized light emission due to their material properties. Prior to this invention, options for polarized white light included using a polarizer (polarizing polymer films) in conjunction with an unpolarized white light source. The problem with these solutions is the energy inefficiency (due to the light absorption by the polarizer), and the high manufacturing cost (due to extra components).
What is needed in the art are improved devices for emitting polarized white light and improved methods of manufacturing such devices. The present invention aims to satisfy this need by simplifying the manufacturing of and decreasing the cost for polarized white light devices.
The present invention may also be used for manipulating the various hues of white light based on LEDs. The applications for this embodiment of the present invention include, but are not limited to, general solid state lighting, backlighting, and architectural lighting applications that require uniform color illumination. Prior to this invention, options for tunable white light included using a number of different colored LEDs (red, green, blue) and changing their intensity individually [1], or introducing different colored, fluorescent, organic dyes as quantum-well light emitting layers [2] or conjugated hybrid polymers [3]. The problems with these solutions are the difficulty in manufacturing, the low efficiency (such as in the organic dyes), and the dependence on multiple light emitters in the first case [1].
What is needed in the art are improved devices for emitting tunable white light and improved methods of manufacturing such devices. The present invention aims to satisfy this need by simplifying the manufacturing of and decreasing the cost for tunable white light devices.